High Voltage Transmission Line Towers Research Articles

Electric field characteristics of shared towers and electric field distribution characteristics near 5G base stations

With the continuous promotion of domestic 4G network construction and the gradual arrival of 5G networks, the requirements of mobile communication networks on capacity and coverage are constantly improving, and the number of communication base stations is also increasing. Therefore, the “shared tower” with the function of a communication base station added to the existing high-voltage transmission line tower is becoming a new resource-sharing mode. There is no systematic study on the installation location of the shared tower base station on the high-voltage tower, which is not conducive to the application and promotion of “shared tower”. In this paper, the finite element simulation model of the tower installed with the base station is built. The electric field distribution near the tower with the base station, the electric field distribution characteristics under different base station installation quantities and different positions of the base station are mainly studied, and the electric field distribution near the surface of the base station is obtained. Combined with the electrical safety distance limit of communication equipment and iron tower, the influence of the installation location and quantity of the base station on the electric field near the base station is evaluated.

Three-dimensional high-efficiency and high-precision modeling of transmission line towers

At present,three-dimensional models of domestic high-voltage transmission line towers mostly rely on professional modelers to refer to the corresponding design parameters and use CAD software to create manually.The workload is large,time-consuming and laborious, and it is difficult to meet the needs of rapid digital modeling of high-voltage transmission line corridors. To this end, a component-based modeling method for the three-dimensional model of the transmission tower is proposed to satisfy the modeler's rapid and high-precision three-dimensional reconstruction of the transmission tower.By decomposing the existing three-dimensional models of different types of power transmission towers, a full-element component model library of power transmission towers is established, so that different components in the model library can be automatically spliced according to their fixed connection relationships.When modeling a specific tower, the user only needs to specify the type and height parameters of the transmission tower, and perform the model direction and the width of the tower head.Fine-tuning can obtain a high-precision three-dimensional model of the transmission tower. This method can reduce the difficulty of three-dimensional modeling of transmission line towers, improve the modeling efficiency, and meet the engineering application needs of rapid digital modeling of power line corridors.

Grounding System Modeling and Evaluation Using Integrated Circuit Based Fast Relaxed Vector Fitting Approach, Considering Soil Ionization

Since high voltage transmission line towers or wind turbines structures are installed in high-altitude areas, it is essential to achieve a high overvoltage protection system against direct and indirect lightning strikes collisions. The lightning current must be discharged quickly into the protective earth, to prevent the dangerous over-voltages formation and define a reference voltage node. This paper presents a novel model to assess the behavior of the grounding system, based on Pocklington integral equations under lightning magnetic fields and variations in soil ionization, in which an explicit circuit-based vector fitting RLC admittance branches are proposed. The frequency-dependent behavior of grounding system frequency response and soil ionization effect is modeled in time domain, straightly to implement into the electro-magnetic transient program (EMTP). The model verification contains horizontal, vertical, and their combinations of grounding grids to represent the complete investigations under lightning strikes. The harmonic impedance mathematical formulations and principles are derived based on a rational function, that could be applicable on ground potential rise (GPR) investigation.

The Research of real-time identification system of types of lightning failures of UHV transmission lines based on UV detection technique

Egineering running experience shows that with the increase of the operating voltage of the transmission line, the lightning trip rate is increasing. According to theoretical calculation ， UHV transmission lines should be provided with full lightning protection characteristics；however，running experience shows that the lightning withstand level of UHV transmission lines is high，not completely lightning protection; it puts forward higher requirements for lightning protection design of UHV transmission line in China. UHV transmission line is mainly against direct lightning stroke characteristics， one is caused by lightning counterattack trip，the other is the shielding failure of lightning around the line to strike the wound caused by the wire. The lightning fault type identification is based on the micro topography of UHV transmission tower，accumulation of historical data，the development of a more targeted and high voltage transmission line lightning protection scheme is of great significance. In this paper, a real-time identification system based on UV detection technology, which has high accuracy and fast response time, is proposed for lightning fault types of UHV transmission lines, the systems use ultraviolet light to realize online detection of high-voltage transmission line tower nearby lightning, can effective observation tower near lightning discharge, and it has the characteristics of continuous detection, longdistance, no power supply, no contact and no disassembly, it provides an advanced technology for the detection of lightning discharge in UHV transmission line.

Ultimate Lateral Bearing Capacity and Group Effect of Belled Wedge Pile Groups

Pile foundation of ports, high-voltage transmission line tower are subjected to amount of lateral loading, prediction on lateral bearing capacity is one of the most important projects in structure design. This paper pertains to the model tests on pile-soil interaction of single pile, 2 × 1 and 2 × 2 belled wedge pile groups embedded in sand under lateral load. The load versus displacement, and the soil pressures along depth surrounding piles are measured, the ultimate lateral bearing capacities and group effects of belled wedge piles are analyzed and discussed. An simplified theoretical calculation method on predicting the lateral bearing capacities of shaped pile groups with considering group pile p-y curves, and longitudinal cross-section variation are proposed. The accuracy and reliability of this developed calculation method are verified through the comparative analysis with model test results obtained in this study and previous literature. The predicted values of lateral bearing capacities have suitable agreement with the measured data. It also shows that the ultimate lateral bearing capacities of belled wedge pile group are nearly 1.8–2.0 times of those of traditional belled pile with the same concrete usage in this study’s condition.

巨厚砂砾岩地层条件下高压线塔压煤开采与变形控制

巨厚砂砾岩地层条件下高压线塔压煤开采与变形控制

Small-diameter vertical shafts constructed in the shallow space of steep mountainous areas

Japan is a mountainous country comprising several islands, in which mountains occupy 70% of the entire land. Therefore, numerous transmission line towers have been constructed in the shallow space of steep mountainous areas. In such construction, monorails and/or cableways are generally used to transport materials and equipment to the construction site instead of using a construction road, as the former method is more economically viable. However, with this method, drill rigs or vertical shaft sinking machines cannot be transported to the site. Four small-diameter vertical shafts of 2.5 or 3.0 m as the foundation for high-voltage transmission line towers in mountainous areas are traditionally constructed manually in Japan. Over the past two decades, however, dangerous and poor environmental conditions for workers regarding the manual construction of these small-diameter vertical shafts have become a major problem. Meanwhile, owing to the poor environmental conditions of small-diameter vertical shafts to be constructed in the shallow space of steep mountainous areas, a decrease has occurred in the number of young workers entering these projects. Namely, the construction of transmission line towers with using the manually traditional small-diameter vertical shafts is becoming difficult in Japan from abovementioned problems. Hence development of a new technology to solve the problems is necessary for Japan’s economic growth. With this knowledge, the authors have developed a new small-diameter vertical shaft construction system, in which workers do not have to enter the vertical shaft during construction, as machines are used instead. The applicability of the proposed system was confirmed by means of the construction of three actual vertical shafts at two construction sites, as well as in factory and field tests. The applicability and details of the final proposed system are summarized in this paper.

Evaluation of High Voltage Transmission Line Towers Footing Earth Resistance under High Impulse Currents

Evaluation of High Voltage Transmission Line Towers Footing Earth Resistance under High Impulse Currents

A Strategy of Suppressing the Underground Impact Scattered Current in Power Grid by Using Insulation Baffle

In order to solve the accidents happened in the ponds or other special places around the tower which were caused by the diffusion current after lightning stroke the transmission tower, the protection measures for the problem tower in the area of Guangdong Province which occurred dead fish in the pond in thunderstorm weather were studied in this paper. The COMSOL mutiphysics simulation software was used in order to calculate the electromagnetic environment of the diffusion situation by grounding device after lightning stroke the power transmission tower. Study concluded that the safe distance between the fish pond and grounding device of transmission tower is 14 meter. The effects of the length and depth or stayed a gap of the insulation baffle on the fish in the fish pond were discussed. The protection method of the insulation baffle has important practical significance to the protection of the grounding device for diffusion current, and can provide some engineering guidance and basis for the grounding arrangement and transformation of the high voltage transmission line tower.

Wavelet-based Analysis of Impulse Grounding Resistance–Experimental Study of the “A”-type Grounding System

This article presents the results of experimental investigation concerned with the “A”-type grounding system's impulse characteristics, which are utilized for grounding of high-voltage transmission line towers. The investigation results point to the presence of high-frequency components in voltage and current signals that are not caused by tower footing response to the impulse current. Additionally, both surge generator coupling and measuring circuit remain their main source. High-frequency components of signals are extracted from voltage and current signals by means of the discrete wavelet transform. In addition to being external influence results, the extracted components have very low energy content as well as short duration. The discrete wavelet transform analysis application has validated the existence of external influences.

Interfacing harmonic electromagnetic models of grounding systems with the EMTP-ATP software package

This paper proposes a methodology for interfacing the frequency-domain harmonic electromagnetic models of complex grounding systems (buried in horizontally stratified multilayer medium) with the EMTP-ATP software package, for the purpose of transient analysis of electrical power systems. It comprises three individual steps: (1) construction of the frequency-dependent nodal admittance matrix for the arbitrarily positioned system of conductors in horizontally stratified multilayer medium, (2) application of the vector fitting technique to this frequency-dependent nodal admittance matrix and (3) construction of the Foster-type networks from the results of the vector fitting and their interfacing with the EMTP-ATP environment. The proposed methodology is general and could be applied to different kinds of grounding systems, ranging from wind turbine grounding systems, to groundings of high voltage transmission line towers and towers carrying GSM base stations.

Numerical Simulation Analysis of High-Voltage Transmission Tower

With the rapid development of Chinese economy construction, hv transmission line has become the main channel for long-distance power transmission and also the most basic conveyance systems and infrastructure for industrial and mining enterprises. The major coal mine fields in China have hv transmission lines passing above. Coal mining subsidence has an important influence on the line tower. So it is important to study the High-voltage transmission line tower to ensure its safety. In this paper, the model is a High-voltage transmission tower. The mechanical analyses for the tower under different boundary conditions are made by finite element simulation. The results can be used as reference for the design of high-voltage transmission line tower in mining area.

Assessment of the backflashover occurrence rate on HV transmission line towers

SUMMARY An assessment of the backflashover occurrence rate on the high voltage (HV) transmission line towers is presented in this paper. It is based on a mathematical model that accounts for the transmission line geometry, keraunic level, statistical distribution of lightning current parameters, and correlation between statistical variables defining the lightning current waveshape. Furthermore, assessment of the backflashover occurrence rate on these towers accounts for the tower footing impulse resistance, lightning impulse insulation strength of the insulator strings and surge impedance of the tower itself. Proposed theoretical analysis is backed by the most recent propositions of parameters that define statistical distributions of lightning current parameters and then applied to the typical HV transmission line example. This analysis might be useful when scrutinizing the several first transmission line towers incoming to the HV substations. Hence, here presented analysis could be subsequently applied for the design of the HV substation overvoltage protection. Finally, a sensitivity analysis is provided, in regards to the parameters of the log-normal distributions defining lightning current amplitude and steepness, as well as in regards to the tower footing impulse resistance. Copyright © 2011 John Wiley & Sons, Ltd.

Parametric analysis of lightning stroke incidence to HV transmission line towers

A parametric analysis of lightning stroke incidence to high voltage (HV) transmission line towers is presented in this paper. It is based on a mathematical model that accounts for the transmission line geometry, keraunic level, statistical distribution of lightning current parameters and correlation between statistical variables defining the lightning current waveshape. Theoretical analysis is backed by the most recent propositions of parameters that define statistical distributions and then applied to the typical HV transmission line example. The results provide insight into the selection procedure for the lightning current parameters (i.e. amplitude, front duration, wave duration and polarity) associated with lightning stroke incidence to transmission line towers. This selection procedure could be applied in backflashover analysis as well as in the analysis (and design) of HV transformer station overvoltage protection. Copyright © 2010 John Wiley & Sons, Ltd.

Magnetic fields produced by power lines do not affect growth, serum melatonin, leukocytes and fledging success in wild kestrels

Nesting on high voltage transmission line towers exposes birds to electric and magnetic fields for long periods. Nestlings are exposed from their development in ovo until fledging. This is a critical period for them because the quality of the developmental environment may affect their fitness at adulthood. We carried out a field study on Eurasian kestrels, Falco tinnunculus, to compare chicks from pairs nesting on high voltage power lines vs. those nesting in control sites in similar habitats. The magnetic field (MF) was measured in each nest-box and analysed in relation to growth curves, melatonin levels, leukocyte counts, and fledging success. None of the variables differed between exposed and control nestlings. Wing length (proxy of age) showed a negative covariation with serum melatonin concentration. Our findings suggest that exposure to MFs produced by high voltage power lines during the embryonic and post-hatching period (until fledging) does not have significant short-term physiological effects on kestrel nestlings.

EHV wood pole fires: Their cause and potential cures

The cause of fires in vertical pole members of wooden high voltage transmission line towers not attributable to surface leakage currents or lightning stroke has been identified as a result of excessive internal Joule losses generated within the pole wood. These Joule losses are a consequence of the electrical conductivity of high moisture content wood and charging currents resulting from the capacitive coupling existing between the poles and the phase wires and high electric field intensities. Suggested cures for the problem include the use of increased numbers of metal fasteners holding the grounding wires to the Poles to more uniformly transfer the charging current from the pole to the grounding network.

A Study of Anchorages for Transmission Tower Foundations

A number of uplift tests have been conducted on anchors proposed for use to support high voltage transmission line towers both for the conventional four legged structure and for the guyed-type structure with a single central footing. Tests were carried out at seven sites, six in the Toronto-Barrie Area and one at Thunder Bay, Ontario. The soil conditions included very dense till, soft clay up to 130 ft (39.62 m) in depth, dense sand and gravel and loose to compact silty sand. The test installations included both power installed multi-helix anchors and grouted anchors with a single reinforcing rod. These were installed at various depths. In the very deep clay only multi-helix anchors were tested. Most of the tests were in uplift on anchors installed vertically. A few group tests were conducted both in uplift and compression. The results of all of the tests are presented along with fairly detailed information on the properties of the soil at each site. An attempt to analyze the results of the helix anchor tests using simplified bearing theory was made. The grouted anchor tests were analyzed using either frictional or adhesive bond theory depending on the soil type. The results indicate that the theories using conventional soil properties provide reasonable design parameters for initial planning. Further confirmation by fullscale testing, however, is essential.